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Peak Design Outdoor Backpack 25L vs REI Co-op Flash Air 50

Weight and specs compared for 2026 — and which one to choose.

REI Co-op Flash Air 50 is the lighter option — 282 g lighter than the Peak Design Outdoor Backpack 25L (25% less weight). If grams matter to you, that is the one to beat.
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Spec Peak Design Outdoor Backpack 25L REI Co-op Flash Air 50
Weight 1,150 g · 1.150 kg · 2.54 lb 868 g · 0.868 kg · 1.91 lb
Brand Peak Design REI Co-op
Category Backpack Backpack
Peak Design Outdoor Backpack 25L
1,150 g

Versatile hiking daypack with Terra Shell™ weather-resistant fabric, roll-top Ultra-Cinch closure (expands from 20-25L), and laptop sleeve. Hiking and everyday...

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REI Co-op Flash Air 50
868 g

Ultralight 50L pack with 3D contoured hip belt and ventilated back panel. Made from PFAS-free UHMWPE fabric with DWR coating.

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Peak Design Outdoor Backpack 25L vs REI Co-op Flash Air 50: which should you buy?

If saving weight is your priority, the REI Co-op Flash Air 50 wins — at 868 g it is 282 g (25%) lighter than the Peak Design Outdoor Backpack 25L (1,150 g). That said, the heavier option may justify the extra grams with more capacity, durability or comfort, so weigh the trade-off against how you'll use it.

See where both rank against everything else in this category on the lightest backpack page, or browse the full gear weight database.

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